The purpose of this study is to clarify the role of family genetic and family environmental influences in the development of alcoholism. In pursuing this objective, we will implement a twin-family design whereby data are obtained from MZ and DZ co-twins who are concordant and discordant for alcoholism and from their spouses and adult offspring. The opportunity to obtain such data is made available by our access to the Vietnam Era Twin (VET) Registry, a nationally distributed panel of over thirty-two hundred twin pairs recently assessed using structured psychiatric interviews. Given these data, we will be able to address four specific aims: (1) To determine the extent to which offspring of alcoholic versus nonalcoholic co-twins differ in regards to alcohol abuse, other psychopathology, and socio-educational-occupational- interpersonal achievements; (2) To determine how genetic and environmental influences vary in relation to different types of paternal alcoholism; (3) To determine the genetic and nongenetic contributions that spouse influences make in accounting for offspring outcomes; and (4) To determine what moderators and mediators associated with childhood (in particular, behavioral undercontrol and affect regulation) and young adulthood (in particular, young adult transition events, social networks, and young adult-parent relationships) serve to qualify and/or account for risk-outcome relationships and what kinds of influences best explain these associations. In this effort, we are particularly interested in understanding gene-environment correlations and gene- environment interactions that characterize the development and expression of alcoholism, drawing on the powerful yet infrequently used twin family design. Beyond simply estimating the strength of genetic/environmental influences, we hope to identify and clarify genetically-based and environmentally-based influences that help explain how family history of alcoholism predisposes individuals to alcoholism outcomes, and that increase or decrease the likelihood of adverse outcomes among high risk individuals.